1. Technical Field
The present invention relates to a displaying method for field sequential color systems using two color fields, and more particularly to a displaying method for field sequential color displays using two color fields.
2. Description of Related Art
Recently, with the development of the display industry, not only the manufacturing processes of display devices gradually advance to maturity, but also the displaying technology for use with such devices is constantly improved. For example, the field sequential color (FSC) technique, which is applicable to and thus denominates various field sequential color display devices including projectors, FSC liquid crystal displays (LCDs) and so on, can enrich the image quality of display devices and enhance system performance, in addition to lowering production costs.
The field sequential color technique works principally by sequentially displaying monochromatic fields of different colors so that, through time integration by the human visual system, or better known as persistence of vision, the monochromatic fields are visually overlapped to form a full color image according to the principle of additive color mixing. A field sequential color display can show color images in the absence of color filters by controlling the colors of a multi-primary backlight module and changing pixel transmittance or reflectance of a light valve element (e.g., an LCD panel). Hence, the electro-optical conversion efficiency of a field sequential color system is increased while the cost of color filters is saved.
A conventional field sequential color display requires at least the three primary color fields to form a full color image. In other words, the displaying frequency of the color fields must be 180 Hz or above to satisfy such a driving mode. However, in order to cope with a field sequential color LCD having a high displaying frequency of color fields, the liquid crystal cells of the LCD must have a short response time, so that a fast-response liquid crystal mode must be used. As a result, field sequential color LCDs, for example, cannot be mass-produced for commercial use due to the high cost of such liquid crystal mode.
In addition, a field sequential color display is susceptible to serious color break-up (CBU) when driven at a color field displaying frequency of 180 Hz. A paper presented at the 2005 International Display Workshops (IDW) and titled “A comparison of three different field sequential color displays” compares three displaying methods. The conclusion of the paper is that two-field FSC methods have less visible CBU than the three-field (red-green-blue) FSC method. However, the two-field FSC methods described in that paper still depend on the use of color filters and thus lose the advantages considerably.